At present, the most common communication systems are radio frequency (RF) based systems. That is why RF systems are also commonly used in vehicle-to-vehicle communication. Such vehicle-to-vehicle communication is used between two vehicles or also in vehicle groups sometimes called a “platoon” or “convoy”. In platoon communications, in general, there is a team leader, and other vehicles follow the team leader. Communication between the vehicles in a platoon may be required for platoons formed by commercial vehicles, civil vehicles, military vehicles, etc. that follow each other. A large problem faced by RF techniques used in this type of communication is that purposeful or purposeless RF signals coming from outside the platoon may affect and/or distort intra-platoon communications. This in turn creates problems both in terms of security and reliability.
Line-of-Sight (LOS) communication systems that provide a directional beam pattern are suitable to solve this security problem. In particular, visible light communication (VLC) has emerged as an alternative and/or complementary to RF based communication solutions. In contrast to RF, which uses frequency bands up to 300 GHz, VLC uses 380-790 THz bands.
There are some important advantages of using optical communication systems like VLC instead of RF in platoons. By use of such optical communication systems in a platoon, security and reliability problems of RF signals may be overcome because the VLC signal is not easily disturbed from outside due to its short transmission range and line-of-sight nature. In such systems, a receiver and a transmitter that “see” each other directly or angularly may communicate without being exposed to an external effect and without being perceived by the receiver of a third party. Non-successive vehicles may communicate by multi-hop communications. A VLC-based platoon is more advantageous than a RF-based platoon in these respects.
Accordingly, inter-vehicle communication is a promising area in which VLC can be applied. In particular, data transmitted from front and rear headlights of vehicles can be received by other vehicles via photodetectors. Prior publications include academic studies as to which type of communication may in general be established physically between two vehicles (modulation type, light beam angle, environmental effects, etc.). Likewise, there are patents or patent applications on inter-vehicle VLC based communications. However, these studies, patents, and applications are generally directed to communication between two vehicles and are not suited for robust intra-platoon communication between multiple vehicles which may or may not be linear and/or successive (i.e., consecutive).
Thus, there is a need for a robust, reliable, and secure communication system and method between commercial, civil and/or military vehicles in a platoon that allows each vehicle to communicate with any other vehicle in the platoon.